O-benzyl-p-chlorophenol substantially completely free from p-chlorophenol as an impurity and its production by distillation with acetophenone

ABSTRACT

O-BENZYL-P-CHLOROPHENOL WHICH IS SUBSTANTIALLY COMPLETELY FREE FROM P-CHLOROPHENOL AS AN IMPURITY IS PRODUCED BY DISTILLING O-BENZYL-P-CHLOROPHENOL CONTAINING PCHLOROPHENOL AS AN IMPURITY WITH A SMALL PROPORTION OF ACETOPHENONE, SEPARATING THE FIRST RUNNINGS AND RECOVERING THE O-BENZYL-P-CHLOROPHENOL WHICH IS THUS SUBSTANTIALLY COMPLETELY FREE FROM P-CHLOROPHENOL AS AN IMPURITY.

United States Patent o-BENZYL-p-CHLOROPHENOL SUESTANTIALLY COMPLETELY FREE FROM p-CHLOROPHE- N 0L AS AN IMPURITY AND ITS PRODUCTION BY DISTHLATION WITH ACETOPHENONE Werner Schulte-Huermann, Kret'eld-Bockum, Germany,

assignor to Farbeufahrikeu Bayer Aktiengesellschaft,

Leverltusen, Germany No Drawing. Filed Apr. 27, 1970, Ser. No. 32,466 Claims priority, application Germany, May 2, 1969,

P 19 22 410.3 Int. Cl. B0111 3/34 U.S. Cl. 203-62 Claims ABSTRACT OF THE DHSCLOSURE o-Benzyl-p-chlorophenol which is substantially completely free from p-chlorophenol as an impurity is produced by distilling o-benzyl-p-chlorophenol containing pchlorophenol as an impurity with a small proportion of acetophenone, separating the first runnings and recovering the o-benzyLp-chlorophenol which is thus substantially completely free from p-chlorophenol as an impurity.

The present invention is concerned with o-benzyl-pchlorophenol which is substantially completely free from p-chlorophenol as an impurity and the production thereof.

More particularly, the present invention is concerned with the production of o-benzyl-p-chlorophenol substantially free from p-chlorophenol as an impurity, from obenzyl-p-chlorophenol containing up to 3% p-chlorophenol. The o-benzyl-p-chlorophenol produced according to the present invention is useful as a bactericidal agent and is particularly useful as a bactericidal agent for incorporation into preparations which are applied to the skin, particularly in the cosmetic field such as skinbeautifying agents. The substantially complete removal of p-chlorophenol thus results in an elimination of the phenol-like odor which would otherwise make objectionable the use of technical grade o-benzyl-p-chloropheno1. In the cosmetic field it is particularly important to eliminate the phenol-like odor. Technical grade o-benzyl-pchlorophenol usually contains from 0.3 to 1.5% by weight p-chlorophenol and it is this percentage of p-chlorophenol as an impurity which gives the o-benzyl-p-chlorophenol an intense phenol-like odor and renders its use unacceptable in cosmetic preparations. The substantially pure product according to the present invention has a pleasant odor resembling that of oil of bitter almonds and thus the o-benzyl-p-chlorophenol according to the present invention has special applicability in the cosmetic field.

In essence, the present invention comprises starting with a technical grade o-benzyl-p-chlorophenol which contains p-chlorophenol as an impurity and distilling the obenzyl-p-chlorophenol with a small proportion of acetophenone and separating the first runnings. This process produces o-benzyl-p-chlorophenol which is substantially completely free from p-chlorophenol as an impurity and is also substantially completely free from any acetophenone as an impurity.

Attempts to utilize known purification methods such as fractional distillation in order to purify o-benZyl-pchlorophenol have proved unsuccessful. Even removing up to 40% by weight as first runnings has not enabled fractional distillation to produce an acceptable product whereby the o-benzyl-p-chlorophenol is substantially completely free of the p-chlorophenol impurity. Equally unsuccessful are recrystallization techniques utilizing various solvents such as washing out with 10%-strength solution of sodium carbonate, distillation with steam and blowing out with various solvents.

It is only according to the present invention that the p-chlorophenol impurity can be substantially completely removed.

According to the present invention the o-benzyl-pchlorophenol starting material may contain up to 3% by weight of p-chlorophenol as an impurity. The amount of acetophenone required in the distillation step may vary in the range of 1% to 20% by weight based on the obenzyl-p-chlorophenol starting material. It is preferred to use about 3% to about 6% acetophenone and especially about 4% to about 5%. The removal of the first runnings preferably amounts to about 8% to about 12% by weight. It has been found that this percentage range is sutficient to produce the good effect in the distillation. If desired, the separated first runnings can be recycled and this can be conveniently done when the process of the present invention is operated as a continuous process.

The distillation can generally be carried out at a pressure range of from about 0.001 to about mm. Hg and preferably at about 0.5 to about 15 mm. Hg.

According to the process of the present invention, one obtains a product which is substantially completely free from p-chlorophenol as an impurity and from acetophenone used in the distillation step. The purity of the product has been determined by gas chromatographic analysis.

The substantially completely pure product of the present invention has a pleasant odor resembling that of oil of bitter almond which makes the use of the o-benzyl-p chlorophenol as a bactericide particularly useful in preparations which are applied to the skin and especially useful in the cosmetic field.

The present invention also includes medicinal and toilet preparations especially cosmetic preparations containing the o-benzyl-p-chlorophenol of the present invention in admixture with any adjuvant or extender. Adjuvants and extenders are well known in both the medicinal and toiletry fields and any of the known adjuvants or extenders can be used in combination with the o-benzylp-chlo-rophenol produced.

The following example illustrates the process of the present invention and the purity of the o-benzyl-p-chlorophenol produced.

EXAMPLE 480 g. of a technical-grade o-benzyl-p-chlorphenol with a solidification point of 42.2 C., and composed of Percent by weight o-Benzyl-p-chlorophenol 90.6 o-Benzylphenol 8.9 p-Chlorophenol 0.5

pleasantly like oil of bitter almonds and with a melting point of 43.8 C. and composed of Percent by Weight o-benzyl-p-chlorophenol 92. 0 o-benzylphenol 8.0

According to gas-chromatography analysis, the product so obtained contains no p-chlorophenol or acetophenone.

Patented Oct. 3, 1972 The presence of o-benzylphenol, Whose activity spectrum is similar to that of o-benzyl-p-chlorophenol, is not troublesome.

The present invention also includes bactericidal compositions which are especially useful for application to mammalian skin comprising o-benZyl-p-chlorophen0l which is substantially completely free from p-chlorophenol as an impurity, in combination with a suitable adjuvant or extender.

What is claimed is:

1. A process for the purification of impure o-benzylp-chlorophenol containing p-chlorophenol as an impurity so as to yield o-benzyl-p-chlorophenol substantially free of p-chlorophenol which comprises mixing a small proportion of acetophenone with the impure o-benzyl-p-chlorophenol, distilling this mixture, separating the initial distillate and collecting as the principal distillate o-benzylp-chlorophenol substantially free from p-chlorophenol.

2. A process according to claim 1 wherein the amount of acetophenone added is from 1% to 20% by weight based on the weight of the impure o-benzyl-p-chlorophenol starting material.

3. A process according to claim 2 wherein the amount of acetophenone added is from 3% to 6% by weight based on the weight of the impure o-benzyl-p-chlorophenol starting material.

4. A process according to claim 3 wherein the amount of acetophenone added is from 4% to 5% by weight based on the weight of the impure o-benzyl-p-chlorophenol starting material.

5. A process according to claim 1 wherein the initial distillate comprise about 8% to 12% by weight of the total distillate.

6. A process according to claim 1 wherein the distillation is conducted under a pressure of from about 0.001 to 100 mm. Hg.

7. A process according to claim 6 wherein the distillation is conducted under a pressure of from about 0.5 to 15 mm. Hg.

8. A process according to claim 1 wherein the impure o-benzyl-p-chlorophenol contains up to 3% by weight p-chlorophenol.

9. A process according to claim 1 wherein the initial distillate is continuously returned to the distillation residue.

10. A process for the removal from a mixture of o-benzyl-p-chlorophenol and o-benzylphenol of the impurity p-chlorophenol which comprises adding to said mixture containing p-chlorophenol about 4%, by weight, of acetophenone so as to form a second mixture, distilling said second mixture at about 4 mm. Hg pressure, separating the initial distillate comprising 8% to 9% by weight of the total distillate and collecting the principal distillate composed of about 92% o-benzyl-p-chlorophenol and about 8% o-benzylphenol.

References Cited UNITED STATES PATENTS 1,967,825 7/1934 Klarmann 260 -619 R 2,925,361 2/1960 Bollenback 260619 R 3,011,940 12/1961 Bollenback 260619 R FOREIGN PATENTS 734,567 4/1943 Germany 2606l9 R WILBUR L. BASCOMB, JR., Primary Examiner US. Cl. X.R. 

